The hydrazine derivatives represented by the general formula (I) which are used as an active ingredient of the ectoparasitic insect pest controllers for animals of this invention are known compounds disclosed in JP-A-5-4958, JP-A-5-17428, JP-A-5-32603 and JP-A-5-262712, wherein is mentioned that these compounds, as an agrihorticultural insecticide, have a controlling effect on Lepidopterous insect pests such as diamondback moth (Plutella xylostella (Linnaeus)), rice leafroller (Cnaphalocrosis medinalis (Guenee)), etc.; Hemipterous insect pests such as tea green leafhopper (Empoasca onukii Matsuda), pear lace bug (Stephanitis nashi Esaki et Takeya), etc.; Coleopterous insect pests such as twenty-eight-spotted ladybird (Epilachna vigintioctopunctata (Fabricius)), maize weevil (Sitophilus zeamais Motschulsky), etc.; Dipterous insect pests such as melon fly (Dacus (Zeugodacus) cucurbitae Coquillett), muscid flies (Muscidae), Culex pipiens molestus, etc.; and tylenchid insect pests such as coffee root lesion nematode (Pratylenchus coffeae (Zimmermann) Filipjev et Schuurmans Stekhoven), root-knot nematode (Meloidogyne sp.), etc. However, in the above-mentioned prior arts, neither mention nor suggestion is made as to the insecticidal effect of these compounds on the ectoparasitic insect pests of animals such as insect pests belonging to fleas, lice and ticks.
A variety of chemicals have so far been proposed as an agent for controlling the ectoparasitic insect pests harmful to bred animals such as domestic and pet animals. However, an agent capable of exhibiting a high controlling effect on the ectoparasitic insect pests at a low dose is not yet known, and creation of such a novel agent is waited for.
The present inventors have conducted extensive studies with the aim of creating a novel agent exerting a remarkable controlling effect on the ectoparasitic insect pests of domestic and pet animals at a low dose. As a result, it has been found that some of the compounds selected from the hydrazine derivatives described in the above-mentioned prior arts have a remarkable controlling effect on the ectoparasitic insect pests of animals. Based on this finding, this invention has been accomplished.